Satellite subscription radio (Sirius/XM) offers a few dozen stations with adult content that is not suitable to be heard by children due to either the subject matter and/or the language. When passengers enter a parked vehicle before or along with the driver (ex., their spouse, children, work colleagues, boss, clients, friends, neighbors, etc.) the last station the driver had listened to from the previous drive cycle will come on and may allow unpredictable content or language to be audible. Further, some automotive OEMs, such as Ford, also allow the radio control head to operate without a key (for up to an hour or until battery charge is at risk) such that the radio can be turned on even without the key and/or present.
Additionally, even if the audio was or is turned down, the presets favorites on the radio display can visually show the listening preferences of the driver to passengers. Depending on the personality/life preferences of both the driver and the passengers, this may create an awkward and uncomfortable situation for the vehicle driver, potential embarrassment, and even potentially harm relationships such as those with clients, employers, or others that may not approve. Such situations can change relationships.
The same risks may also exist with less controversial subject matter such as a genre of music, political talk radio, NASCAR, religious programming, or other topics on which passengers may have opinions that could affect their relationship with the driver. The driver may wish to keep their personal life/interests private.
The same privacy principles could also apply to terrestrial radio stations and imported multimedia formats a driver may bring to the vehicle such as Cassettes, MP3 players, jump drives, CDs, SD cards, Bluetooth Streaming, WiFi streaming, and any method of playback. Concerned drivers could just shut down these media formats or radio bands when they leave the vehicle, but they may forget or did not expect to have passengers for the next drive cycle when they parked.